The invention relates to an airbag module having an airbag comprised of a fabric, and a gas generator, arranged in a pocket of the airbag, whereby the gas generator has projecting pin-shaped securing means which project through openings in the airbag.
An airbag module with the aforementioned features is known from DE 195 32 369 A1. The corresponding airbag has, based on its substantially cylindrical shape in the inflated state, a laterally attached pocket for receiving the gas generator whereby the pocket is matched to the inner contour of the airbag module housing which receives the gas generator and the folded airbag. The edge portion of the pocket is sewn onto the fabric of the main portion of the airbag by a circumferential seam. The pocket of the airbag comprises a plurality of openings aligned with corresponding bores in the housing of the airbag module through which pin-shaped securing means for fastening the airbag module to a vehicle part. Such an airbag design of two individual parts sewn together is complicated and expensive, and assembly of airbag and gas generator to an airbag module is cumbersome.
A one-part design of an airbag with attached pocket is disclosed in EP 0 471 762 B1. In this known arrangement, the two fabric layers which form the airbag have a flap-like projection whereby, upon assembly of the airbag arrangement, the gas generator is placed between the two projections of the fabric layers and these fabric layers are placed with partial embracing of the gas generator about the gas generator. For attachment of the two separate flap-shaped projections to the gas generator, the gas generator is provided with pin-shaped projections spaced in the longitudinal direction to one another, and the two flap-shaped projections of the fabric layers have matching openings so that the two flap-shaped projections can be fastened at the gas generator by placing the openings provided therein onto the pin-shaped projections. This known arrangement has the disadvantage that the assembly of the airbag module is complicated because the two individual flap-shaped projections must be placed separately about the gas generator, and their openings must be threaded onto the projections of the gas generator. Furthermore, sealing of the airbag in the area of the receiving chamber provided by the flap-shaped projections for receiving the gas generator is often not satisfactory.
Further such embodiments of an airbag with overlapping flaps for mounting the gas generator at the airbag are known from DE 44 23 552 A1 or EP 0 633 168 A1.
The invention has the object to improve an airbag module with the aforementioned features in regard to assembly and sealing of the airbag in the area of the gas generator receiving means.
The invention provides according to its basic idea that the two fabric layers enveloping the gas generator are connected to one another by a seam and the seam for forming the pocket has a lateral offset and that at at least one part of the offset a flap is provided which is folded over and secured with at least one opening on the pin-shaped fastening means of the gas generator.
The invention has the advantage that the embodiment of a receiving pocket for the gas generator, already accomplished during manufacture of the airbag by weaving and/or sewing, reduces the assembly expenditure is because assembly only requires the gas generator to be inserted into the pocket whereby the openings provided in the area of the pocket are then oriented toward the pin-shaped securing means projecting from the gas generator. Subsequently, only the overlapping portion in the form of a flap in the area of the offset must be folded over and must be placed with its corresponding openings also onto the pin-shaped fastening means. By this folding action, the plays remaining in the area of the pocket upon formation of the pocket because of the fastening means projecting from the gas generator, is eliminated so that the double layer of the airbag fabric resulting from folding over the seam area provides an improved total sealing action of the airbag. Due to the arrangement of the gas generator in the seam area of the airbag fabric the fabric, loading occurring during inflation of the gas bag is received and distributed in an improved manner whereby, because of the large surface area contact of the airbag fabric at the gas generator, the forces acting on the airbag are minimized. At the openings in the airbag fabric for receiving the securing means essentially no forces will occur.
According to one embodiment of the invention it is suggested that the outer seam at one end of the pocket is closed and the pocket at its other end is provided with an insertion opening for the gas generator; this arrangement has the advantage that the sealing action of the airbag portion for receiving the gas generator is further improved because leakage can only occur in the area of the insertion opening. These leakages, however, are eliminated especially by the inventive folding over of the excess seam portion in the form of a flap.
For improving the assembly, it may be provided that the insertion opening of the pocket has a diverging portion and the flaplaterally projecting that is to be folded over the gas generator extends into the area of the diverging portion of the insertion opening. With this diverging portion the mounting opening for the gas generator is increased so that assembly is facilitated and an easy alignment of the gas generator is ensured.
One embodiment of the invention suggests that over the length of the gas generator two pin-shaped projections are arranged and that the pocket and the flap of the seam have correlated openings.
In a unknown manner the manufacture of the outer seam according to embodiments of the invention can be realized by sewing the two fabric layers together or by providing a woven connection of the two fabric layers during weaving of the airbag.
According to one embodiment of the invention, the securing means can be embodied as fastening screws that can be threaded into correlated bores and project from the gas generator.
It may be provided that the securing means serve, in addition to securing the airbag, also asr attachment meansof the gas generator at a vehicle structure such as the steering wheel, etc., so that accordingly these securing means have a double function.